Study On Electromagnetic Compatibility Test And Diagnosis Technology Based On Wavelet Analysis Theory

Electromagnetic Compatibility (EMC) is a cross-disciplinary science based on electromagnetism including such multi-disciplinary as information science, electrical engineering, electronics, communications, materials and structures, etc. It is also an applied technology, which is used to study, under the conditions of limited space, limited time and limited frequency resources, the compatibility of electrical and electronic devices and systems within the common electromagnetic enviroment without a degradation of performance. The international society attachs importance to the EMC and some developed countries and regions bring it into the state抯 law system, thus forming a trade bulwark. The study range of EMC is very extendsive and the problem of EMC is very complex. The EMC testing technology is one focus of the EMC research field. The EMC testing technology includes testing equipment, testing method, data processing and result evaluation. The Fourier analysis is the foundation theory of electromagnetic interfere (EMJ) testing study. According to the characteristics of EMI signal and mathematics principle of Fourier analysis, this paper explains the localization of Fourier analysis method in the EMI testing. The time characteristics of EMI testing signal is a useful imformation of electromagnetic disturbance source also, such as starting time, duration time, and the different frequency of electromagnetic disturbance source in the different time. Under condition above, this paper points out the validity of a time-frequency analytic method and demonstrates the feasibility of an EMI diagnosis based on wavelet analysis theory. Some EMI diagnosis simulation results and case study resulting from multi-resolution wavelet analysis and wavelet packet analysis are also given in this paper, which proves that wavelet analysis method is of validity. This paper brings forward some common technological problems about typical household appliances?EMC according to EMC testing, and gives some countermeasures use to anti-interfere in the typical household appliances. An EMC problem due to a PWM inverter applied in air-condition is analyze carefully.